Refrigerator & Icemaker Repair
A vast majority of the refrigerators built within the last 30-40 years (and thus most likely to still be in service) were built using the systems described in Chapter 1; however, there are a few exceptions:
Certain refrigerators use hot Freon circulated backwards through the evaporator to melt frost, rather than an electric heater. Though there are more recent models, these are generally built in the 1960's and before and represent a very small minority of the domestic refrigerators still in service.
These units do not have a timer that initiates the defrost mode. Some must be initiated manually (usually there is an obvious defrost button) and some have no defrost at all — they must be unloaded, unplugged, and let defrost by themselves.
These refrigerators have a very cold plate or coils (tubes) located near the top of the cold compartment. There is no evaporator fan and air circulates naturally. By convection, warm air rises to the top of the compartment where the coils are, and the cold air sinks towards the bottom.
There may be separate plates in the freezer and refrigerator sections. Often these refrigerators have no defrost systems; if they do, it's usually a hot-gas defrost system. Most "micro-" or "mini-" fridges are chill-type. Most freezer (only) units have no evaporator fans. Generally these units have no condenser fan either; condenser air circulation is also by convection.
IF YOU HAVE A "GAS" REFRIGERATOR, NOTHING IN THIS BOOK APPLIES TO YOUR UNIT. It uses an entirely different operating system; it is NOT a vapor-compression-cycle unit. These are generally found in RV and yacht installations, where electricity is frequently unavailable for extended periods of time.
If you suspect that you may have any of these units, ask your appliance parts retailer or dealer to confirm your suspicions. (See Section 3-1; "BEFORE YOU START.") With a make, a model number and perhaps a serial number, he should be able to tell you what you have.